of innovations and research, corporation for supportive housing, new haven, connecticut. robert kershaw, business owner and outreach worker, oxford house, incorporated, silver spring, maryland. dr. jesse b. milby, director, medical psychology, substance abuse and homeless research program, department of psychology, university of alabama at birmingham, birmingham, alabama. dr. clark, when is a person categorized as homeless? well, the most important thing is to recognize that when a person lacks a permanent, fixed residence, they meet the category of homeless. now, there are a number of temporary arrangements that people have; for instance, it's estimated that roughly 1.6 million people are living in transitional or shelters, and they also meet the definition of homeless. so it's-we're looking for people who have permanent, fixed residence, and if you don't have that, then you're defined as homeless.